​STRUCTURE AND FUNCTION OF THE EYE

The eye consists of several parts that are somewhat similar to a camera

 Sclera: the white material which we normally see as the white of the eye. It is the eye‘s outer protective coat.

 Cornea: the transparent, curved structure at the front of the eye

 Iris: through the cornea the iris can be seen, which is that part of the eye which gives it colour – blue, brown, green, grey etc. It is a circular muscle which responds to bright light by contracting, making the pupil smaller.

 Pupil: in the middle of the iris is the pupil, a transparent aperture which appears black. ​

The pupil constricts in response to bright light and dilates in low levels of light.

 Lens: situated immediately behind the iris and pupil is a transparent disc with both sides being convex. The lens focuses light onto the retina. It divides the eye into two parts – anterior and posterior chambers.

 Anterior Chamber: a fluid with the consistency of water circulates around this chamber. This fluid is called the aqueous humour.

 Posterior Chamber: this is filled by the vitreous humour which has the appearance of transparent jelly.

 Retina: situated at the back of the eye, the retina consists of millions of nerve cells which are divided into two main groups – rods and cones. They are so described because of their appearance under a microscope.

 Cones: concentrated around an area of the retina called the macula.

 Rods: although some are placed near the macula, the majority of rods are spread out to cover the rest of the retina.

 Retinal Pigment Epithelium: a dark coloured layer of cells underlying the retina responsible for providing oxygen and other nutrients to the rods and cones.

 Choroid: located behind the retina, it consists of a large network of blood vessels that transport oxygen and other nutrients to the retinal pigment cells.

 Optic Disc: the nerve cell connections from all the rods and cones travel to the optic disc, a small, yellow, oval structure which can be seen through an ophthalmoscope.

 Optic Nerve and beyond: the optic disc is the front part of the optic nerve which passes from the eye to make connections throughout the brain.​

​THE USHER SYNDROME EYE:The eye condition those with Usher syndrome suffer with is Retinitis Pigmentosa (RP). RP is caused by a degeneration of the cells at the back of the eye reducing the persons ability to see in dark conditions, along with a narrowing of the field of vision. You can read more about RP in the next section RETINITIS PIGMENTOSA.